Not Applicable
Not Applicable
This invention relates to the field of intravascular medical devices, and more particularly to the field of catheters such as angioplasty, neurological and guide catheters, among others, which may be used in various medical procedures such as percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA) as well as in procedures involving the placement of medicines and medical devices within the body. The present invention is directed to all forms of catheters which may be advanced through a body lumen or vessel. Some examples of catheters are over-the-wire (OTW) catheters, such as are described in U.S. Pat. No. 5,047,045; single-operator-exchange (SOE) balloon catheters, such as are described in U.S. Pat. No. 5,156,594 and U.S. Pat. No. 5,549,552. Other examples of catheters which may incorporate the unique features of the present invention are also described in U.S. Pat. No. 5,938,653, U.S. Pat. No. 5,897,537, among others.
The entire content of all of the patents listed within the present patent application are incorporated herein by reference.
Intravascular diseases are commonly treated by relatively non-invasive techniques such as PTA and PTCA. These angioplasty techniques typically involve the use of a balloon catheter. In these procedures, a balloon catheter is advanced through the vasculature of a patient such that the balloon is positioned proximate a restriction in a diseased vessel. The balloon is then inflated and the restriction in the vessel is opened. In other uses a catheter may be used to delivery an endoprosthesis such as a stent, graft, vena cava filter or other implantable device. Where an implantable device is to be delivered into a body lumen the catheter may include one or more inflatable portions or balloons.
Many procedures make use of a guide catheter positioned within the vascular system of a patient. The guiding catheter assists in transporting a balloon dilation catheter, or other form of treatment catheter, to the portion of the vessel requiring treatment or inspection. The guide catheter is urged through the vasculature of the patient until its distal end is proximate the restriction. The balloon catheter may then be fed through a lumen in the guide catheter.
Whether an individual procedure utilizes a guide catheter or simply requires the use of a solitary dilitation or medical device delivery catheter, catheters typically must possess a level of rigidity which will allow it to traverse tortious pathways through blood vessels in a manner that minimizes trauma. The catheter must be capable of being advanced through the vascular system without folding or buckling despite application of longitudinal and/or rotational forces upon the catheter. Because many catheters have the desired rigidity, it is desirable to incorporate a relatively flexible and desirably atraumatic tip on the distal end of the catheter to avoid injury to the walls of the blood vessels as the otherwise comparatively rigid catheter is advanced therethrough.
The present invention provides a catheter with a novel tip or distal end which is sufficiently rigid to avoid kinking and bending as it advances through a lumen, but which is sufficiently soft and flexible such that the tip is less likely to cause trauma to vessel surfaces which it may contact.
The catheter tip may be provided with the desired characteristics by constructing the tip from a combination of at least two materials having different material characteristics such as hardness.
In at least one embodiment of the invention, the catheter tip comprises a first material or matrix and one or more stripes or segments of a second material, wherein the second material is harder than the first material.
As used herein, the term xe2x80x98hardnessxe2x80x99 is used to define a differentiating feature between the first material and the second material. Hardness may be defined using the Shore scale of hardness wherein the second material may have a greater value on the Shore scale of hardness than that of the first material. However, the term xe2x80x98hardnessxe2x80x99 as used herein may be used to denote a measurable difference between the first material and the second material other then that which may be indicated using a Shore hardness test. The hardness as defined by the Shore scale is considered to be a significant feature in differentiating between the first material and the second material, xe2x80x98hardnessxe2x80x99 may also refer to concepts such flexibility, elasticity, tensile modulus, modulus of elasticity, as well as many other characteristics which may be different from one another.
The second material may be characterized as one or more stripes of material imbedded within or engaged to the first material. The stripes of material may be coextruded with the matrix or may be engaged to the matrix after formation of the first material. The stripes of the second material may be uniform in width along the length of the catheter tip. Alternatively the stripes may taper, be intermittent, or otherwise configured. Furthermore, the stripes may be disposed about the matrix in a variety of ways, such as for example, one or more stripes may be helically wound about the tip, multiple stripes may be longitudinally parallel throughout the length of the tip, a stripe or stripes may extend along the length of the tip and tapper toward or away from the end of the tip in increasing or decreasing width.
Other characteristics of the stripe or stripes of secondary material may also be varied relative to the first material matrix. For example, the second material may have a thickness equal to or different from the thickness of the first material.
The stripes of relatively hard secondary material may alternatively be characterized as one or more coatings applied to the surface of the first material.
The second material may also be characterized as one or more fibers or braids of fiber of a predetermined material or combination of materials. The fibers may be oriented relative to the longitudinal axis of the catheter tip in a variety of patterns. For example the fibers may be substantially parallel to the longitudinal axis of the angled relative thereto, helically or otherwise disposed thereabout, etc.
In at least one embodiment of the invention, the stripe(s) of second material may be disposed about the inside and/or outside of the catheter tip.
In yet another embodiment of the invention, the stripes of a second material may be fully enclosed, or xe2x80x9csandwichedxe2x80x9d within the matrix of the first material.
In still another embodiment of the invention the matrix of the catheter tip, i.e. the first material, may itself be comprised of a variety of materials. In such an embodiment the stripe(s) may be enclosed between an inside layer of material and an outside layer of material, wherein the inside material and the outside material are different from one another. In such an embodiment the stripe(s) of second material remain harder than the combined layers of first material.